The one big advantage of Android phones that often turns out to be a big disadvantage for many android users is that these phones can be modified, tinkered, rooted, 'rom'ed and what not.. While this feature of android phones gives unlimited freedom to enhance the capacity of these phones and sometime improve upon the official firmware, it has a big risk of bricking your phone or making your phone really shitty. The other major problems that arise after tinkering/modifying the official firmware is that the official software 'Kies' does not recognize your phone and does not provide official updates, and loss of warranty. So if you have played with your phone and now wants to restore to official firmware here is the step by step guide. This will help you in restoring your phone to Android 2.1 Eclairs and official firmware I9000DDJG4. After restoring your phone to this firmware you can use Kies to upgrade to Android 2.2 Froyo. (Though there is very rare chance of things getting wrong, but there is always a possibility so try at your own risk.)
But before you start the restoration process here are the the files /softwares you need to have (since you modified/flashed your phone, most of you would be having most of these.. or can download)
Odin Vs 1.03 Download (the software to flash your phone)
.Pit file Download pit .512 (required to map the partition in your phone)
I9000DDJG4 Firmware Download (the official firmware for Indian users, the 'DD' in I9000DDJG4 is indicate country code..if you are from other region you can choose appropriate firmware from samsung-firmwares.com .
The firmware file is password protected, Password is: samsung-firmwares.com.
Now if you want to back up your phone using Nindroid google it to get the details.
1. Check the firmware by dialing *#1234#. Note down the current version of the firmware in case something goes wrong and you need to get help.
2. Install Odin on your windows machine.
3. Extract the firmware file in a folder and copy the pit file in the same folder.
4. Switch off your phone and power it on by pressing 'Power Button'+Home+Volume Down button simultaneously. This will boot your phone in 'downloading now' mode.
5. Start odin and connect your phone in 'downloading mode' to your usb port. The software will detect the phone. Now, choose 'repartition', 'reboot' options. And select the downloaded pit file in odin. Now in PDA option choose the extracted firmware file with '.tar' extension. There are two files in the extracted folder but you do not have to do anything with .dll file. Click on start and let the software do the rest. The phone will restart after installing the firmware.
If you phone hangs, just remove the battery and put it back and try again. It will work. Once you have restored the phone check the phone firmware by dialing *#1234#. It should reflect the new firmware 'JG4'
Now you connect your phone to Kies, it will recognize your phone and you can officially upgrade to the 2.2 Froyo firmware supplied by Samsung. This will restore all your warranties as well.